1. Field of the Invention
The present invention relates to a novel DNA whose expression level fluctuates in leukocytes of IgA nephropathy patients in comparison with leukocytes of healthy persons, a process for isolating the DNA, a method for detecting the DNA, a novel protein encoded by the DNA an antibody recognizing the protein, a method for detecting the protein, and diagnosis and treatment of IgA nephropathy.
2. Brief Description of the Background Art
IgA nephropathy is a chronic glomerulonephritis which is characterized in that an IgA immune complex considered to be originated from blood deposits in glomerulus of the kidney. In Japan, the IgA nephropathy occupies 30% or more of primary renal diseases, having the highest frequency as a single renal disease, and 15 to 30% of the disease becomes renal insufficiency due to poor prognosis. However, since the cause of the disease of IgA nephropathy is still unclear, a fundamental therapeutic method has not been found. Additionally, definite diagnosis of IgA nephropathy imposes heavy burden on patients, because the method is carried out by taking out a portion of the kidney by biopsy and recognizing deposition of the IgA immune complex in mesangium by means of an immunological staining.
It has been reported that about 50% of the patients with IgA nephropathy have a high blood IgA level [Diseases of the Kidney, 5th edition (1993), Nephron, 29, 170 (1981)]. It is considered that B cells relate to the production of IgA in blood and T cells relate to the regulation of the production. Furthermore, it has been reported that the production of cytokine, such as interleukin 4, interleukin 5, interleukin 6 or TGF-xcex2 (transforming growth factors), is high in peripheral T cells of IgA nephropathy patients in comparison with healthy persons [Clinical and Experimental Immunology, 103, 125 (1996), Kidney International, 46, 862 (1994)] and that integrin, such as VLA (very late activation)-4 and VLA-5, are strongly activated in peripheral lymphocytes of IgA nephropathy patients [Nephrology, Dialysis, Transplantation, 10, 1342 (1995)]. On the basis of these facts, it is considered that, in IgA nephropathy, the production of IgA becomes excess due to abnormality in the immune system, the resulting IgA immune complex in blood deposits on the glomerulus, and activation of the complement system caused thereby and the like exert influence upon disorders of the glomerulus, but the cause of IgA nephropathy has not been reported.
Elucidation of the cause of IgA nephropathy and its treatment or diagnosis which can reduce a burden on patients are expected.
Accordingly, the present invention provides the development of a novel DNA related to IgA nephropathy, a method for obtaining the DNA, a novel protein related to IgA nephropathy, a method for producing the protein, an antibody recognizing the protein, and a therapeutic drug and a diagnostic drug using the above-described protein, DNA or antibody.
Specifically, the present invention relates to:
(1) a DNA related to IgA nephropathy, comprising a nucleotide sequence selected from the nucleotide sequences represented by SEQ ID NO:1 to NO:32 and SEQ ID NO:39 to NO:42, or a DNA which hybridizes with said DNA under stringent conditions;
(2) a DNA comprising a nucleotide sequence identical to continuous 5 to 60 residues in a nucleotide sequence selected from the nucleotide sequences represented by SEQ ID NO: 1 to NO:32 and SEQ ID NO:39 to NO:42, or a DNA comprising a sequence complementary to said DNA;
(3) a DNA comprising a nucleotide sequence selected from the nucleotide sequences represented by SEQ ID NO: 43 to NO:104;
(4) a method for detecting mRNA of an IgA nephropathy-related gene using the DNA according to any one of the above (1) to (3);
(5) an IgA nephropathy diagnostic agent comprising the DNA according to any one of the above (1) to (3);
(6) a method for inhibiting transcription of an IgA nephropathy-related gene or translation of mRNA of an IgA nephropathy-related gene using the DNA according to the above (2) or (3);
(7) an IgA nephropathy therapeutic agent comprising the DNA according to the above (2) or (3);
(8) a method for isolating a DNA related to IgA nephropathy from leukocytes of a patient with IgA nephropathy comprising conducting a differential display method;
(9) a protein comprising an amino acid sequence selected from the amino acid sequences represented by SEQ ID NO:33 to NO:38; or a protein comprising an amino acid sequence in which one or several amino acids are deleted, substituted or added in the amino acid sequence of said protein, and having an activity related to IgA nephropathy;
(10) a DNA encoding the protein according to the above (9);
(11) a recombinant DNA obtained by inserting the DNA according to the above (10) into a vector;
(12) a transformant obtained by introducing the recombinant DNA according to the above (11) into a host cell;
(13) a method for producing the protein according to the above (9), comprising: culturing the transformant according to the above (12) in a medium to produce and accumulate said protein in the culture; and recovering said protein from the resulting culture;
(14) an antibody which recognizes the protein according to the above (9);
(15) a method for immunologically detecting the protein according to the above (9) using the antibody according to the above (14);
(16) an IgA nephropathy diagnostic agent comprising the antibody according to the above (14);
(17) an IgA nephropathy therapeutic agent comprising the antibody according to the above (14);
(18) a composition comprising the DNA according to any one of the above (1) to (3) and a diagnostic acceptable carrier;
(19) a composition comprising the DNA according to the above (2) or (3) and a pharmaceutical acceptable carrier;
(20) a composition comprising the antibody according to the above (14) and a diagnostic acceptable carrier; and
(21) a composition comprising the antibody according to the above (14) and a pharmaceutical acceptable carrier.